JPS61156631A - Microwave discharge power supply apparatus - Google Patents

Abstract

PURPOSE:To equalize the discharge within every corner of the tube and suppress uneven emission of light by arranging the radiating direction of microwave to the same direction within the microwave propagation chamber and causing the light to be incident on the electrodeless luminous tube under the condition that distribution of light intensity is equalized. CONSTITUTION:The microwave from a microwave output part 13 of a magne tron 12 is sent to an antenna 18 and this microwave is radially emitted to a microwave propagation chamber 22 of a quartz glass bulb 20 from the antenna 18. The external circumference of a bulb 20 including this propagation chamber 22 is covered with a cylinder 25 made of stainless and the microwave is supplied to an electrodeless luminous tube 23 along the vertical direction of antenna 18. This propagation chamber 22 is kept under the vacuum condition and a dielectric loss of propagation chamber 22 is set smaller than that in the luminous tube 23. direction of microwave is arranged uniformly within the propagation chamber 22, distribution of intensity is equalized, the light is made incident on the luminous tube 23 passing through a flat separation plate 21 and thereby uneven emission of light within the luminous tube 23 is suppressed.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a light source device using microwave discharge.

[Technical background of the invention]

Electrodeless lamps using microwave energy as an excitation source not only have a long lifespan, but also have a good output efficiency of ultraviolet light when compared to conventional polarized lamps as ultraviolet light sources. ■Used as a light source for drying curable ink. A rat is being played.

Incidentally, as this type of electrodeless light source device, one having a configuration as shown in FIG. 3, for example, is conventionally known.

That is, inside the box-shaped device main body 1, there is a hollow microwave cavity resonator 3 having an opening 2 at one end for extracting light.
and a magnetron 4 are arranged, and in this cavity resonator 3, the microwave radiated from the microwave output section 5 of the magnetron 4 is transmitted to the waveguide 6 and the circumferential surface of the cavity resonator 3. It is designed to be guided through the power supply lower.

An electrodeless lamp 8 made of, for example, a quartz bulb sealed with a discharge medium is installed in the part of the microwave cavity resonator 3 where the microwave intensity is highest, and the microwave is applied to the electrodeless lamp 8. When applied, a discharge occurs in the internal discharge medium and ultraviolet rays in a predetermined wavelength range are generated.
This ultraviolet light is radiated outward through the opening 2.

[Problems with background technology]

However, in the above-mentioned conventional example, since the microwave is irradiated to the electrodeless lamp 8 from the outside, the microwave does not enter the electrodeless lamp 8 sufficiently, resulting in poor light conversion efficiency. was there.

Therefore, the present inventor considered inserting an antenna that emits microwaves inside an arc tube in which a discharge medium is sealed. In this way, all of the microwaves were irradiated onto the arc tube, making it possible to significantly improve the light conversion efficiency.

By the way, in light processing using such a device, not only a uniform illuminance distribution is required, but also demands such as locally increasing or decreasing the illuminance depending on the type of light processing. may be issued. In such a case, it is preferable to deal with this by changing the shape of the arc tube, but in the above antenna method, the microwave intensity decreases as it moves away from the antenna, so it is of course necessary to make the irradiance uniform. There was a problem in that it was difficult to obtain a desired illuminance distribution. In order to meet such requirements, it is necessary to make at least the intensity distribution of the microwaves irradiated onto the arc tube uniform.

(Object of the invention) The present invention was made based on the above circumstances, and
It is an object of the present invention to provide a microwave discharge light source device in which the intensity distribution of microwaves irradiated to at least an electrodeless arc tube is made uniform.

[Summary of the invention]

That is, in order to achieve the above-mentioned object, the present invention covers an antenna and an electrodeless arc tube with a conductive cylinder having an opening for light extraction at one end, and also covers the antenna and the electrodeless arc tube with a conductive cylinder having an opening for extracting light at one end. By providing a microwave propagation chamber between the electrodeless arc tube and setting the dielectric loss in this microwave propagation chamber smaller than the dielectric loss of the electrodeless arc tube, the micro wave irradiated onto the electrodeless arc tube is It is characterized in that the wave intensity distribution is made uniform within the microwave propagation chamber.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on FIGS. 1 and 2.

In the figure, reference numeral 11 denotes a waveguide for transmitting microwaves, and in this embodiment, a square tube with a rectangular cross section with both ends closed is used. A magnetron 12 that generates microwaves is installed at one end of the waveguide 11, and a microwave output section 13 of this magnetron 12 is connected to a gasket 14.
It is introduced into the waveguide 11 via. Note that reference numeral 15 in the figure indicates a power source for the magnetron 12.

A through hole 16 having a diameter sufficient to allow microwaves to pass through is provided at the other end of the waveguide 11, and a support 1γ made of an electrically insulating material such as Teflon is provided at the center of the through hole 16.
An antenna 18 is inserted through the antenna 18 . The antenna 18 of this embodiment has a hollow cylindrical shape, and one end thereof is introduced into the waveguide 11, and the other end is inserted into the waveguide 11.
1 for a predetermined length. A quartz glass bulb 20 is attached via a bracket 19 to the outer surface of the waveguide 11 from which the antenna 18 is led out. The interior of the quartz glass bulb 20 is partitioned along the tube axis by a partition wall 21 made of quartz glass that has magnetic and translucent properties.

The microwave propagation chamber 22 is airtightly divided into two chambers, one of which is a microwave propagation chamber 22 into which the antenna 18 is coaxially inserted.
, and the other end forms an electrodeless arc tube 23 located on the tip side of the antenna 18 .

In this case, the microwave propagation chamber 22 and the electrodeless arc tube 2
The partition wall 21 that partitions the quartz glass bulb 20
The electrodeless arc tube 23 is formed into a cylindrical shape, and the distal end surface 24 of the electrodeless arc tube 23 facing the partition wall 21 is also finished flat. ing. Therefore, the length of the electrodeless arc tube 23 along the tube axis direction, that is, from the partition wall 21 to the tip surface 24
The length up to this point is the same everywhere on the electrodeless arc tube 23. In the case of this embodiment, the inside of the microwave propagation chamber 22 is maintained at a vacuum level of, for example, 104 to 10 Torr, and a rare gas such as argon (Ar) is used as a discharge medium in the electrodeless arc tube 23. 104～
Several Torr and a predetermined amount of luminescent metal material such as mercury (HQ) are sealed. Therefore, the dielectric loss of the microwave propagation chamber 22 is set to be smaller due to the pressure difference in the rain air and the difference in the sealed substances.

The outer periphery of such a quartz glass bulb 20 is covered with a cylinder 25 made of a conductive material such as stainless steel, and one end of this cylinder 25 located on the electrodeless arc tube 23 side is provided with a An opening 27 for light extraction facing the surface 26
has been established. Note that this opening 27 allows light to pass through, but there is a wire mesh 2 to prevent microwave leakage.
8 is posted.

Further, in the case of this embodiment, a partition wall tube 29 made of quartz glass is attached to the support 17 that supports the antenna 18 to airtightly cover the periphery of the antenna 18. A cooling pipe 31 made of glass is connected, and the antenna 18 is cooled by outside air blown through the cooling pipe 31. The outside air that has cooled the antenna 18 is then passed through the waveguide 11 through the communication hole 32 provided in the bulkhead tube 30 and the support 17.
It is designed to escape inside.

In addition, the reference numeral 33 in FIG. 1 is a plunger for minimizing the reflected waves of the microwave and efficiently transmitting the microwave to the antenna 1.8.

Next, the operation of the above configuration will be explained.

Microwaves radiated from the microwave output section 13 of the magnetron 12 are transmitted to the antenna 18 through the waveguide 11, and are transmitted to the quartz glass bulb 2 via the antenna 18.
0 radially into the microwave propagation chamber 22. Note that this emitted microwave is transmitted to the microwave propagation chamber 2.
This microwave propagation chamber 22
Since the inside is kept in a vacuum atmosphere and dielectric loss is small, no discharge occurs. Since the outer periphery of the quartz glass bulb 20 including the microwave propagation chamber 22 is covered with a stainless steel cylindrical body 25, the microwaves emitted in the radial direction are In this way, the direction is forcibly changed along the axial direction of the antenna 18 without transmitting through the cylinder 25. Therefore, in the microwave propagation chamber 22, the direction of the microwaves is aligned toward the electrodeless arc tube 23, so the intensity distribution of the microwaves is equalized, and the evenly distributed microwaves become flat. The light passes through the partition wall 21 and enters the electrodeless arc tube 23 from its entire surface.

As a result, uniform discharge (plasma) is excited within the electrodeless arc tube 23, and in this case, the length of the electrodeless arc tube 23 along the tube axis direction is Since the discharge is uniform, uniform discharge is started throughout the electrodeless arc tube 23, and the ultraviolet rays generated by this discharge are transmitted through the wire mesh 28 and irradiated onto the irradiated surface 26.

According to such an embodiment of the present invention, the direction of the microwave is aligned in advance in the same direction within the microwave propagation tube 22, and the electrodeless light emission in which the discharge medium is enclosed is made with the intensity distribution equalized. Since the light is made to enter the tube 23, the discharge inside the electrodeless arc tube 23 is equalized throughout the corner, and uneven light emission can be suppressed to a small level. Therefore, as shown in FIG. 2, it is possible to equalize the irradiance (μw/ci) on the irradiated surface 26 that is a certain length away from the opening 27 of the cylinder 25, and this irradiance is Even if the input/output of the magnetron 12 is changed, there is no difference, and treatments with different amounts of ultraviolet irradiation can be performed continuously.

Particularly in the case of this embodiment, since no discharge is started within the microwave propagation tube 22, other light does not mix with the light generated within the electrodeless arc tube 23, further suppressing uneven light emission. be able to.

At the same time, if the electrodeless arc tube 23 is made cylindrical and the above length L is secured, even if there is a slight variation in the microwaves incident on the electrodeless arc tube 23, this variation can be absorbed. This effectively contributes to suppressing uneven light emission.

In addition, since the discharge within the electrodeless arc tube 23 is equalized as described above, when the distribution of irradiance on the irradiated surface 26 is locally increased or decreased, for example, the electrodeless This problem can be solved by simply changing the above-mentioned length L partially by adding irregularities to the partition wall 21 or the tip end surface 24 of the arc tube 23. Therefore, the distribution of irradiance can be changed simply by changing the shape of the quartz glass bulb 20, making it easier to partially change the irradiance than in the past, and making it easier to set the irradiance. This has the advantage of increasing the degree of freedom.

In the above embodiments, the electrodeless arc tube has a cylindrical shape, but it may also have a flat disk shape, for example. Furthermore, the discharge medium sealed in the electrodeless arc tube is not limited to mercury, but may be any material suitable for the light to be obtained. For example, hydrogen, krypton or xenon gas or a mixture thereof may be used as required.

Further, the electrodeless arc tube and the microwave propagation chamber may be configured with separate quartz glass bulbs, and the microwave propagation chamber is not limited to a vacuum. The same kind of gas as the one used may be sealed in a more dilute state than in the electrodeless arc tube.

Alternatively, the waveguide may be omitted and the microwave output section (antenna) of the magnetron may be directly inserted into the microwave propagation chamber of the electrodeless arc tube.

Furthermore, in order to change the illuminance distribution, in addition to changing the shape of the arc tube, various methods can be considered, such as installing a filter.

〔Effect of the invention〕

According to the present invention described in detail above, microwave radiation is possible.

The opposite directions are aligned in the same direction in the microwave propagation chamber, and the intensity distribution is made equal before entering the electrodeless arc tube. Therefore, the discharge inside the electrodeless arc tube is equalized to every corner, resulting in uneven light emission. It has the advantage of being able to keep it small.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the present invention, with Figure 1 being a sectional view, Figure 2 being a characteristic diagram showing the distribution of irradiance, and Figure 3 being a characteristic diagram showing the distribution of irradiance.
The figure is a schematic configuration diagram of a conventional microwave discharge light source device. 12... Magnetron, 18... Antenna, 20.
...quartz glass bulb, 22...microphone A-wave propagation sky,
23... Electrodeless arc tube, 25... Cylindrical body, 21...
Opening.

Claims (2)

[Claims] (1) An antenna that emits microwaves generated by a magnetron, an electrodeless arc tube that encapsulates a discharge medium that is discharged by the microwaves, and an electrodeless arc tube that surrounds the antenna and electrodeless arc tube, and has a light extraction tube at one end. a conductive cylindrical body having an opening for the purpose of the present invention; a microwave propagation chamber, wherein dielectric loss in the microwave propagation chamber is set smaller than dielectric loss in the electrodeless arc tube. (2) The microwave discharge light source device according to claim (1), wherein the microwave propagation chamber is vacuumed.